Few days ago, I opened the front stereo receiver, without disconnecting the battery, and unplugged the a/c controls behind it. ( I needed to adjust the speaker wires behind the stereo receiver)

The next morning, my battery seemed to have lost a lot of power, but the car still cranked. Took it for a drive and noticed that the compressor fan was still running, even with the car off. I unplugged it so it wouldn't drain the battery, and reconnected it when I had to leave.

Could the relay be the problem? I checked the fuses and they're not blown.

 

Found the problem. The relay, the big block on the most-bottom left, is stuck open. Switched it with the relay on the other side and the fan turned off.

Off to autozone